The latest nationwide fitness trend has been compared to a cult and criticized for being elitist.

But "military style" is, perhaps, the best description for CrossFit ­-- a high-intensity workout that throws a constantly varying lineup of strength- and endurance-based moves at participants to prepare them for any physical challenge. A typical Workout of the Day (which CrossFitters call WODs) -- five rounds of 15 pullups and 15 wall balls ­-- would make any Marine feel right at home.

It began in the late 1990s, when the first gym opened on the West Coast, and by 2005, there were more than 1,500 gyms operating. These days, the number of CrossFit centers has exceeded 4,500 in the continental United States, including 77 in Connecticut -- and 18 in Southwestern Connecticut, including five in Stamford, two in Danbury, and centers in Fairfield, Monroe and Milford, among others.

To learn more about CrossFit, a trend I heard described as "cult-like" and "too intense," I signed up for a three-week on-ramp training course at Iron Resolve CrossFit, in Stamford, which was opened in March by Felipe Polanco and Mike Nguyen.

My on-ramp, which ran Monday, Tuesday and Thursday nights, had about 10 people in it. During the first week, when we were still in the High Ridge facility, quarters were tight. But by week two, it was like working out in an empty bowling alley ­-- a super hot and sweaty, turf-lined bowling alley.

The CrossFit franchise is known for its intensity, but at Iron Resolve, there is an everyman aspect of the fitness fad. The people in my on-ramp ranged in age from their 20s to 40s, and our sizes and fitness levels were just as varied. From the couple who wanted to get back into shape after their first year of marriage, to 42-year-old Lana Buccieri who was looking for a fitness trend she would finally love, to the new employee at a hedge fund where almost everyone on staff swore by the workout, reasons for joining ran the gamut.

So did our expectations.

"One of my goals was just to be able to do a single pullup," Buccieri said this week. She is through the on-ramp now, and has been heading to the gym three or four times a week for the past six weeks. "I haven't gotten that far. I'm still doing ring rows, but I know each time I go, I get a little bit stronger."

She has to scale a lot ­-- meaning she rarely does the prescribed workout, but uses a smaller amount of weight or modifies a skill such as pullups or handstand pushups -- but that's fine with her.

"In an odd way, it's very comforting," she said. "It sounds ridiculous, but it's comforting to have such a wide variety of people, because Felipe really tries to get you to focus on competing against yourself . . . Having all the different levels reminds you of where you've been and where you can get to, and it still makes you feel OK that you are where you are. And that camaraderie, it makes a big difference."

The scaling is fine with Polanco, too, who said he would rather see people in his gym focus on form until they nail it than see them hurt themselves because they weren't prepared.

"What good does that do, if you lift a ton of weight and break something or hurt yourself? Then you're out. Then it's not fun, because you're hurt," he said over coffee last month.

Injuries and stupidity have, at times, given CrossFit a bad reputation, and that's not something Polanco wants to be part of, he said.

In addition to concerns about injuries, CrossFit has been criticized for elitism, with membership makeup consisting of one-percenters. That criticism has some credence; there are plenty of hedge funders on the gym's roster, and at about $200 a month, the membership price demands a more affluent crowd than your typical chain gym such as LA Fitness or New York Sports Club.

But on that Monday night in early July, there were three people in the 5 p.m. class -- a 32-year-old registered nurse, a 36-year-old teacher and a 55-year-old North Stamford resident -- all grunting as they thrust metal barbells over their heads.

"Yeah, we have a lot of hedge funders and blah blah blah, but if you think about it, those guys, they're really type-A, competitive people, and that's what CrossFit is," Polanco said.

"CrossFit is what you make of it," he continued. "It can either be as competitive as all hell, and that's where the hedge fund guys come in, or it can be just going in for a kick-ass workout, which is what our 73-year-old guy does -- he scales stuff, but he comes in for a workout and a laugh and then he leaves."

At first, the idea of performing some of these WODs can be just as paralyzing as if someone asked you to hike Mount Everest, but after a while, it's all in a day's play. For example, on the first night of on-ramp, people are told to complete four rounds of five burpees, 10 situps and 15 squats as quickly as possible. For a 27-year-old reporter who's let her body settle into a softer form than she would like over the past couple of years, it sounded like a daunting challenge, and I completed it in six minutes and three seconds.

"The look on your face that first night, it was clear, you were just all about survival," Polanco told me a few weeks later as I admitted just how terrified I'd been in the beginning, before cutting my time down to four minutes and 44 seconds during the last session. "But then that last night, I saw this switch flip and it's like you were out for blood."

Buccieri's experience was similar. On the first night, she didn't quite make it through all the movements in the prescribed time. But three weeks later, I chanted and screamed with the former stranger as I counted her reps, "You're gonna finish in time, Lana! You're gonna do it!"

She did, in around 7½ minutes, a moment she described as a total victory, and the moment that sold her on the program.

"I think people, they hear you describing it or trying to describe it, and you just always feel like you have to say, `You had to be there,'" she said this week. "And once you explained it, or you found like a YouTube clip you can show them, they look at you, as if to say, `Are you kidding me? You do this?' But since you've started doing it, it doesn't feel nearly as intimidating. You think, `Wow. If I can do this, what else can I do?'"

That's the feeling that keeps the trend growing, and feeds Polanco's confidence in the idea that taking the risk to open his gym was indeed a safe bet.